Image reading apparatus and image forming apparatus

ABSTRACT

An image reading apparatus for reading image information from a sheet includes a cover unit, a sheet feeding member, a conveying guide, and a reading unit including a transparent member and a reading portion. The cover unit is rotatable between a closed position where the cover unit forms a sheet conveying passage in cooperation with the conveying guide and an open position where the sheet conveying passage is open. In a state in which the cover unit is positioned in the closed position, the transparent member is exposed to an outside of the image reading apparatus by rotation of the conveying guide and the reading unit.

FIELD OF THE INVENTION AND RELATED ART

The present invention relates to an image reading apparatus for readingimage information from a sheet and an image forming apparatus forforming an image on a recording material.

Conventionally, in the image reading apparatus mounted in a copyingmachine or the like, one in which a reading unit is provided inside anautomatic document (original) feeder (ADF) for feeding originals whileseparating the originals one by one has been known. In the case wherethe reading unit is provided inside the AFD, in order to clean a glasssurface opposing the original and the eliminate (clear) an original jam,a conveying passage is constituted openably so that the glass surface ofthe reading unit is exposed to an outside of the image reading apparatusin some cases. In Japanese Laid-Open Patent Application (JP-A)2016-220232, a constitution in which in order to expose the glasssurface of the reading unit to the outside of the image readingapparatus, a conveying guide member provided below the conveying passageof the ADF is rotated is disclosed.

However, in the constitution disclosed in JP-A 2016-220232, a use makesaccess the glass surface of the reading unit from below the ADF. In sucha case, there is a need to clean the glass surface in a manner such thatthe user looks into the reading unit from below the ADF, and therefore,there was a problem that the glass surface is not readily cleaned.

SUMMARY OF THE INVENTION

A principal object of the present invention is to provide an imagereading apparatus capable of facilitating cleaning of a glass surface ofa reading unit and to provide an image forming apparatus including theimage reading apparatus.

According to an aspect of the present invention, there is provided animage reading apparatus for reading image information from a sheet,comprising: a cover unit provided rotatably about a first rotationalaxis and including an upper surface of the image reading apparatus; asheet conveying member configured to convey the sheet along a sheetconveying passage; a conveying guide provided rotatably about a secondrotational axis different from the first rotational axis and configuredto guide the sheet fed by the sheet conveying member; and a reading unitwhich includes a transparent member and a reading portion configured toread, through the transparent member, an image on the sheet fed by thesheet conveying member and which is provided rotatably about a thirdrotational axis different from the first rotational axis and the secondrotational axis, wherein the cover unit is rotatable between a closedposition where the cover unit forms the sheet conveying passage incooperation with the conveying guide and an open position where thesheet conveying passage is open, and wherein in a state in which thecover unit is positioned in the open position, the transparent member isexposed to an outside of the image reading apparatus by rotation of theconveying guide and the reading unit.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic view of an image forming apparatus according toan embodiment, FIG. 1B is a schematic view of an original readingapparatus in the embodiment, and FIG. 1C is a schematic view of theoriginal reading apparatus in a state in which an upper cover is open.

FIG. 2 is a schematic view showing a part of an ADF according to anembodiment 1.

FIG. 3 is a sectional view of a reading unit according to the embodiment1 and a periphery of the reading unit.

FIG. 4 is a sectional view of the reading unit in a cutting positionshown in FIG. 2 and a periphery of the reading unit.

FIG. 5A and FIG. 5B are schematic views for illustrating movement of arotation guide and the reading unit in the embodiment 1.

FIG. 6 is a schematic view showing a state in which the reading unit inthe embodiment 1 is moved to a maintenance position.

FIG. 7 is a schematic view for illustrating a force acting from an armon the reading unit.

FIG. 8 is a schematic view for illustrating a maximum rotation angle inthe case where the arm originals only one surface of the reading unit.

FIG. 9 is a schematic view showing a part of an ADF according to amodified embodiment.

FIG. 10 is a schematic view showing a part of an ADF according to anembodiment 2.

FIG. 11 is a schematic view showing the part of the ADF according to theembodiment 2.

FIG. 12 is a schematic view showing the part of the ADF according to theembodiment 2.

FIG. 13 is a schematic view showing a part of an ADF according to anembodiment 3.

FIG. 14 is a schematic view showing the part of the ADF according to theembodiment 3.

FIG. 15 is a schematic view showing an ADF according to an embodiment 4.

FIG. 16 is a schematic view showing the ADF according to the embodiment4.

FIG. 17A, FIG. 17B and FIG. 17C are schematic views each showing anelectric wire connected to the reading unit in the embodiment 1.

FIG. 18 is a schematic view showing an ADF according to an embodiment 5.

FIG. 19 is a schematic view showing the ADF according to the embodiment5.

FIG. 20 is a schematic view showing an ADF according to an embodiment 6.

FIG. 21 is a schematic view showing the ADF according to the embodiment6.

DESCRIPTION OF THE EMBODIMENTS

In the following, embodiments according to the present invention will bedescribed with reference to the drawings.

[Image Forming Apparatus]

First, a schematic structure of an image forming apparatus 1 accordingto an embodiment will be described using FIG. 1A. The image formingapparatus 1 of this embodiment is a color electrophotographic apparatusincluding, as image forming means, an image forming mechanism 1Bincluding four image forming portions PY, PM, PC and PK. The imageforming apparatus 1 forms an image on a sheet S on the basis of imageinformation received from an original reading apparatus 2 provided at anupper portion of an apparatus main assembly 1A or from an externaldevice. As the sheet which is a recording material, it is possible touse a variety of sheet materials different in size and material,including papers such as plain paper and thick paper, a plastic film, acloth, a surface-treated sheet material such as coated paper,special-shaped sheet materials such as an envelope and index paper, andthe like.

The image forming apparatus 1 includes a main controller 12. The maincontroller 12 includes a CPU as an executing means for executing acontrol program for the image forming apparatus 1, an ROM for storing aprogram, an RAM for temporarily storing data, and an input/outputcircuit for inputting and outputting signals between itself and anoutside. The CPU reads the program from the ROM and then executes theprogram, and provides instructions to respective portions of the imageforming apparatus 1 through the input/output circuit, so that the CPUcontrols an operation of the image forming apparatus 1. For example, themain controller 12 is electrically connected to a controller 2C of theoriginal reading apparatus 2. The main controller 12 receives the imageinformation read from an original by reading units 110 and 210 throughthe controller 2C and then is capable of performing an image formingoperation (copying) for forming, on the sheet S, an image based on thereceived image information.

The image forming portions PY, PM, PC and PK are units for forming tonerimages of yellow, magenta, cyan and black, respectively. The imageforming portions PY to PK are also called process units or image formingstations. The four image forming portions PY to PK have thesubstantially same constitution except that colors of toners used forforming the toner images are different from each other. Each of theimage forming portions PY to PK includes a photosensitive drum 3 whichis a photosensitive member formed in a drum shape, and as process meansactable on the photosensitive member and for executing anelectrophotographic means, such as charging device 4, a developingdevice 6, and a drum cleaner 8. Below each of the image forming portionsPY to PK, an exposure device 5 as the process means (exposure means) forexposing the associated photosensitive drum 3 to light is provided.Above each of the image forming portions PY to PK, a supply container 9for supplying a developer to an associated developing device 6 ismounted detachably mountable to the apparatus main assembly 1A.

Above the image forming portions PY to PK, an intermediary transfer unit19 is provided. The intermediary transfer unit 19 includes anintermediary transfer belt 21 which is an intermediary transfer memberconstituted by an endless flexible member, and a plurality of rollersfor stretching the intermediary transfer belt 21. The plurality ofrollers includes an inner secondary transfer roller 22. On an outerperiphery side, a secondary transfer roller 23 is provided at a positionopposing the inner secondary transfer roller 22 while sandwiching theintermediary transfer belt 21 therebetween. As a nip between thesecondary transfer roller 23 and the inner secondary transfer roller 22,a transfer portion (secondary transfer portion T2) where an image istransferred from the intermediary transfer belt 21 onto the sheet S isformed. On an inner peripheral side of the intermediary transfer belt21, at a position opposing each photosensitive drum 3, a primarytransfer roller 7 is provided while sandwiching the intermediarytransfer belt 21 therebetween. Further, on the outer peripheral side ofthe intermediary transfer belt 21, a belt cleaner 24 is provided.

At a lower portion of the apparatus main assembly 1A, a sheet feedingportion for feeding sheets S is provided. The sheet feeding portionincludes a cassette 40 provided detachably mountable to the apparatusmain assembly 1A and a feeding unit for feeding the sheets S, stackedand accommodated in the cassette 40, while separating the sheets S oneby one. On a feeding passage from the sheet feeding portion to thesecondary transfer portion T2, a feeding roller pair 41 and aregistration roller pair 42 are provided.

On a side downstream of the secondary transfer portion T2 with respectto a sheet feeding direction, a fixing device 30 is provided. The fixingdevice 30 includes a fixing roller 31 as a heating member, a pressingroller 32 as a pressing member, and an unshown heating means for heatingthe fixing roller 31. As the heating means, it is possible to use ahalogen lamp and a heating unit of an electromagnetic induction type. Ona side further downstream of the fixing device 30, a discharging roller43 as a discharging means for discharging the sheet S, on which theimage is formed, to an outside of the apparatus main assembly 1A isprovided. At an upper surface portion of the apparatus main assembly 1A,a discharge tray 11 as a stacking portion on which the sheets, on whichthe images are formed, are to be stacked is provided. This embodimentemploys a constitution of a so-called in-body discharge type in which aspace in which the sheets S, on which the images are formed, are to bedischarged and stacked is formed between the apparatus main assembly 1Aand the original reading apparatus 2 with respect to an up-downdirection (vertical direction in the case where the image formingapparatus 1 is installed on a horizontal surface).

When the main controller 12 receives image information and an executioninstruction of an image forming operation, the main controller 12,execute the image forming operation in a following manner. First, ineach of the image forming portions PY to PK, rotation of thephotosensitive drum 3 is started, and then the surface of thephotosensitive drum 3 is electrically charged uniformly to apredetermined polarity and a predetermined potential by the chargingdevice 4. The surface of the photosensitive drum 3 is irradiated with(exposed to) laser light modulated depending on an image signal (videosignal) based on the image information, so that an electrostatic latentimage corresponding to a component image of an associated color ofyellow, magenta, cyan and black is written (formed) on thephotosensitive drum 3. The resultant electrostatic latent images aredeveloped with develops containing toners of the respective colors, sothat toner images of yellow, magenta, cyan and black are prepared on thephotosensitive drums 3. The toner images carried on the photosensitivedrums 3 are primary-transferred from the photosensitive drums 3 onto theintermediary transfer belt 21 by the primary transfer rollers 7. At thistime, the toner images of the respective colors are superposed on eachother on the intermediary transfer belt 21, so that an image as afull-color image is formed on the intermediary transfer belt 21. Adeposited matter such as transfer residual toner remaining on thesurface of the photosensitive drum 3 without being transferred onto theintermediary transfer belt 21 is removed by the drum cleaner 8. Theimage formed on the intermediary transfer belt 21 is conveyed to thesecondary transfer portion T2 by rotation of the intermediary transferbelt 21.

In parallel to a toner image forming process in each of the imageforming portions PY to PK, one sheet S is fed from the cassette 40 andis conveyed to the registration roller pair 42 through the feedingroller pair 41. The registration roller pair 42 corrects obliquemovement of the sheet S, and thereafter conveys the sheet S to thesecondary transfer portion T2 so that arrival of the image, carried onthe intermediary transfer belt 21, at the secondary transfer portion T2and arrival of the sheet S at the secondary transfer portion T2 aresynchronized with each other. In the secondary transfer portion T2, theimage is transferred (secondary-transferred) from the intermediarytransfer belt 21 onto the sheet S under application of a bias voltage tothe secondary transfer roller 23. A deposited matter such as the tonerremaining on the intermediary transfer belt 21 without being transferredon the sheet S is removed by a belt cleaner 24.

The sheet S passed through the secondary transfer portion T2 is conveyedto the fixing device 30. The fixing device 30 heats and presses theimage on the sheet S while nipping and feeding the sheet S in a nip(fixing nip) between the fixing roller 31 and the pressing roller 32. Bythis, the toner is melted and color-mixed and then is fixed, so that theimage fixed on the sheet S is obtained. The sheet S passed through thefixing device 30 is discharged by discharging roller 43, so that thesheet S is stacked on a discharge tray 11. By this, a series of imageforming operations is ended.

Incidentally, in this embodiment, the color electrophotographicapparatus of the intermediary transfer type was described as an example,but the image forming apparatus 1 may include an image forming means ofa direct transfer type in which a toner image formed on an image bearingmember is transferred onto the sheet S without through the intermediarytransfer member. Further, an image forming type is not limited to theelectrophotographic type, and the image forming apparatus 1 may alsoinclude, as the image forming means, a printing unit of an ink jet typeor an offset printing mechanism.

[Original Reading Apparatus]

The original reading apparatus 2 which is an example of the imagereading apparatus will be described using FIG. 1B. The original readingapparatus 2 includes a scanner portion (main body portion, lower portionunit) 20 and an ADF 10 provided on an upper portion of the scannerportion 20 and used as an upper unit supported rotatably by the scannerportion 20. The original reading apparatus 2 is capable of executing anoperation for reading image information from a static original placed onan original supporting platen glass of the scanner portion 20 (fixedreading operation) and an operation for reading the image informationwhile feeding a sheet as an original by the ADF 10 (moving(skimming-through) reading operation).

The scanner portion 20 includes the original supporting platen glass onwhich the original is to be placed and a reading unit 210 for readingthe image information of the original placed on the original supportingplaten glass while moving below the original supporting platen glass ina sub-scan direction (left-right direction) in FIG. 1B. Further, thescanner portion 20 includes a glass 201 as a transparent member. Thereading unit 210 is capable of reading the image information byoptically scanning the original, fed by the ADF 10, through the glass201.

The reading unit 210 includes a sensor substrate 213 on which a CCDimage sensor as a light receiving element is mounted, an illuminationportion 211 for illuminating the original with light, and a reductionoptical system including a plurality of mirrors 212 and for imagingreflected light from the original onto an imaging surface of the lightreceiving element. In this embodiment, the reading unit 210 of a CCDtype is shown, but a reading unit 210 of a CIS type in which thereflected light from the original is imaged on an imaging surface of aCMOS sensor, provided opposed to the original, through a 1:1magnification optical system. The image information read by the readingunit 210 is transmitted to a controller 2C through a signal line 151.

The ADF 10 includes an original tray 121, a discharge tray 122, an ADFmain body 10A in which an original conveying passage P1 is formed, and areading unit 110 provided along the original conveying passage P1. Inthe ADF main body 10A, as a sheet feeding (conveying) member for feeding(conveying) the sheet, a feeding roller 101, a separation roller pair102, conveying roller pairs 103, 104 and 105, and a discharging rollerpair 106 are provided along the original conveying passage P1. Theoriginal tray 121 is a stacking portion on which sheets are to bestacked, and the discharge tray 122 is a discharge portion where thesheet from which the image information is read is discharged. Theoriginal tray 121 is positioned above the discharge tray 122, and asviewed from a point of view of FIG. 1B (in a state viewed in a sheetwidthwise direction), the original conveying passage P1 is curved in aU-shaped which open toward one side of the horizontal direction.

The reading unit 110 includes a contact image sensor (CIS) 112 as areading portion, a reading frame 119 for holding the CIS 112, and aglass 111 (see also FIG. 3 ). The glass 111 is a transparent memberopposing the original conveying passage (sheet conveying passage) P1,and the CIS 112 functions as a reading portion for reading the imageinformation from the original (sheet), conveyed along the originalconveying passage P1, through the transparent member.

The reading frame 119 and the glass 111 form a substantially rectangularparallelopiped-shaped space for accommodating the CIS 112. The CIS 112includes a sensor substrate 112 c on which a CMOS image sensor as alight receiving element is mounted, an illumination portion forilluminating the original with light, and a lens 112 b for constitutinga 1:1 optical system for imaging the reflected light, from the original,on an imaging surface of the light receiving element (see also FIG. 3 ).In this embodiment, the reading unit 110 of a CIS type is shown, but animage sensor unit of a CCD type may be used as the reading unit 110. Theimage information read by the reading unit is transmitted to thecontroller 2C through an electric wire 150. A wiring path of theelectric wire 150 will be specifically described.

An original feeding (conveying) operation by the ADF 10 will bedescribed using FIG. 1B. When a user sets an original bundle on theoriginal tray 121 and provides a start instruction of a readingoperation through an unshown operating portion, the sheets are fed fromthe original tray 121 by the feeding roller 101 in an order from anuppermost original. The fed sheet is conveyed in a state in which thesheets are separated one by one by the separation roller pair 102 andthen conveyed along the original conveying passage P1 while successivelydelivered by the conveying roller pairs 103, 104 and 105.

Then, when the original passes through the glass 201 of the scannerportion 20, image information of a first side of the original is read bythe reading unit 210. Similarly, when the original passes through theglass 111, image information of a second side opposite from the firstside of the original is read by the CIS 112 of the reading unit 110. Theoriginal from which the pieces of image information are read isdischarged to an outside of the ADF main body 10A by the dischargingroller pair 106 and then is stacked on the discharge tray 122.

In the following description and drawing, the vertical direction in astate in which the image forming apparatus 1 is installed on thehorizontal surface is referred to as a “Z-direction”. A sheet widthwisedirection perpendicular to the original feeding direction of theoriginal fed along the original conveying passage P1 is referred to asan “X-direction”. The X-direction is a main scan direction during imagereading and may preferably be a direction (horizontal direction)perpendicular to the Z-direction. The horizontal direction as viewed inthe X-direction is referred to as a “Y-direction”. The X-direction, theY-direction, and the Z-direction are directions crossing each other andmay preferably be directions perpendicular to each other.

Incidentally, as shown in FIG. 1B, the ADF 10 includes an upper portioncover 147 as a cover unit constituting an upper surface portion of theADF main body 10A. The upper portion cover 147 is rotatably supported bya frame of the ADF main body 10A through a supporting portion 147 a, andis rotatable about an axis (first rotational axis) extending in theX-direction. The upper portion cover 147 is provided with a conveyingguide 148 as an opposing guide (upper-side guiding surface) forming theoriginal conveying passage P1 between itself and a guiding surface(lower-side guiding surface) of a rotation guide 141 supported by theADF main body 10A. As shown in FIG. 1B, in a state in which the upperportion cover 147 is closed, a state in which a part of the rotationguide 141 is covered with the upper portion cover 147 is formed. Here,in the state in which the upper portion cover 147 is closed, entirety ofthe rotation guide 141 may also be covered with the upper portion cover147. Further, the upper portion cover 147 is provided with the feedingroller 101, one (upper-side roller in the figure) of the separationroller pair 102, and one (upper-side roller in the figure) of theconveying roller pair 103. Accordingly, when the upper portion cover 147is rotated from a closed position shown in FIG. 1B to an open positionshown in FIG. 1C, a part of the original conveying passage P1 is opened,so that the rotation guide 141 is exposed to an outside of the ADF 10,and thus a state in which the rotation guide 141 is capable of beingrotated as described later.

[Glass Cleaning]

Incidentally, during repetition of the moving reading operation of theoriginal reading apparatus 2, foreign matters including dust such aspaper powder, and contaminants such as paste (adhesive) and ink whichhave been deposited on the original are deposited on the glasses 201 and111 in some cases. When the moving reading operation is performed in astate in which the foreign matters are deposited on the glasses 201 and111 within reading ranges of the reading units 210 and 110, stripeimages which do not originally exist on the original are read atpositions corresponding to the foreign matters. This phenomenon iscaused by a shadow created by blocking an optical path, during readingby the reading units 210 and 110, with the foreign matters deposited onthe glasses 201 and 111 (hereinafter, this phenomenon is referred to asan “image stripe(s)”).

In order to eliminate an occurrence of the image stripe, removal of theforeign matters, causing the occurrence of the image stripe, throughappropriate cleaning of the glasses 201 and 111 is effective. As regardsthe reading unit 210 of the scanner portion 20, the glass 201 of thereading unit 210 is exposed by rotating the ADF 10 upward, andtherefore, the glass 201 can be cleaned from above. On the other hand,the reading unit 110 of the ADF 10 is disposed inside the ADF main body10A. As shown in FIG. 1B, in this embodiment, the reading unit 110 isdisposed in an inside region of the original conveying passage P1 formedbelow the rotation guide 141 and curved in a U-shape. For that reason, aconstitution for exposing the glass 111 to the outside (means forenabling access to the glass 111) is needed.

Here, as a method of exposing the glass 111 of the reading unit 110 tothe outside, a constitution in which the reading unit 110 is supportedby the rotation guide 141 and is rotated integrally with the rotationguide 141 would be considered. However, in such a constitution, thereading unit 110 is rotated integrally with the rotation guide 141, andtherefore, when the rotation guide abuts against another member, impactdepending on an entire weight of a rotatable unit including the readingunit 110 and the rotation guide 141 generates. The reading unit 110 is aprecise device in which an electronic circuit including a lightreceiving element, and optical elements constituting an illuminationportion and a 1:1 optical system or a reduction optical system areprovided. For that reason, in the case where the rotation guide 141 isrotated for exposing the glass 111 to the outside, when large impact isexerted on the reading unit 110, there is a possibility that insidecomponent parts are broken or displaced.

Therefore, as described in the following, in this embodiment, aconstitution in which not only the rotation guide 141 as a rotatableconveying guide is provided but also the reading unit 110 is maderotatable, independently of the rotation guide 141, about a rotationalaxis different from the rotational axis of the rotation guide 141 isemployed. By rotating the rotation guide 141 and the reading unit 110,the glass 111 which is a surface opposing a sheet (object to be read) ofthe reading unit 110 is exposed to the outside. By this, the impactexerted on the reading unit 110 when the reading unit 110 is moved forperforming the cleaning of the glass 111 or jam clearance can bereduced. Further, by employing a constitution in which the reading unit110 is made rotatable independently of the rotation guide 141, stressexerted on the electric wire connecting the reading unit 110 and thecontroller 2C to each other can also be reduced.

In the following, specific constitutions of the reading unit 110 and aperiphery thereof will be described while citing embodiments.

Embodiment 1

First, an embodiment 1 will be described using FIGS. 2 to 7 . FIG. 2 isa side view showing a part of components of the ADF 10. In thisembodiment, in the case where the ADF 10 is viewed in the X-directionfrom a front surface side of the image forming apparatus 1, memberspositioned inside the original conveying passage P1, and a baseconveying guide 143 and an arm 131 are shown in FIG. 2 . FIG. 3 is asectional view of the reading unit 110 cut along a plane perpendicularto the X-direction.

As shown in FIGS. 2 and 3 , to a bottom (opening of the reading frame119 having a substantially U-shape in cross section) of the reading unit110 in which the CIS 112 is incorporated, the glass 111 is stuck.Further, to each of opposite end portions of the glass 111 with respectto the X-direction (longitudinal direction of the CIS 112, main scandirection), a gap sheet 115 is stuck.

FIG. 4 shows a state of an IV-IV cross section of FIG. 2 . Incidentally,the IV-IV cross section is a cross section obtained by cutting thereading unit 110 along a plane (plane extending in the X-direction and asheet thickness direction D2 at a scanning position) perpendicular to asheet feeding direction D1 at the scanning position of the reading unit110. As shown in FIG. 2 and FIG. 4 , each of the two gap sheets 115stuck to (mounted on) the opposite end portions of the glass 111 withrespect to the X-direction abuts against a shading plate 144 which is anopposing member opposing the glass 111. As a result, in a region(original passing region) between the gap sheets 115 with respect to theX-direction, as shown in FIG. 3 , a gap corresponding to a thickness ofthe gap sheets 115 is ensured between the glass 111 and the shadingplate 144. That is, the gap sheets 115 function as a gap forming memberfor forming a gap between the glass 111 and the opposing member incontact with the opposing member opposing the glass 111. The gap formingmember is not limited to the gap sheets 115 when the member ensures(defines) a width (range) of the gap, and for example, a projectionprojecting toward the glass 111 may be formed integrally with thereading frame 119.

Incidentally, the shading plate 144 is mounted on the base conveyingguide 143 which is a conveying guide opposing the reading unit 110, andthe base conveying guide 143 is mounted on the frame of the ADF 10. Thatis, the shading plate 144 and the base conveying guide 143 are membersfixed to the frame of the ADF 10.

Further, a pressing portion 114 for pressing the reading unit 110 isprovided so stat the reading unit 110 is stably at rest at abutmentpositions of the glass sheets 115 (FIG. 4 ).

The pressing portion 114 is provided at an upper portion (on a sideopposite from the glass 111) of the reading unit 110. The pressingportion 114 includes a resin cover 114 a as a contacted portioncontacted to a pressing surface 141 a (FIG. 2 ) provided on the bottomof the rotation guide 141, and a compression spring 114 b as an elasticmember interposed between the resin cover 114 a and the reading frame119.

The rotation guide 141 includes a shaft portion 141 c rotatablysupported by the frame of the ADF 10 and is rotatable about a rotationalaxis A1 (second rotational axis). In this embodiment, the rotationalaxis A1 is provided at an upstream end (one-side end portion withrespect to the Y-direction) of the rotation guide 141 with respect tothe sheet feeding direction of the sheet fed from the feeding roller 101toward the separation roller pair 102, but may also be provided atanother position. Further, a supporting portion is not limited to theshaft portion 141 c when the supporting portion is a supporting portionfor rotatably supporting the rotation guide 141, and the rotation guide141 may be provided with a hole (bearing portion) in which ashaft-shaped portion provided on the frame of the ADF 10 is engageable.The rotation guide 141 is rotatable between a position for guiding alower surface of the original fed along the original conveying passageP1 (see FIG. 2 , hereinafter, this position is referred to as a closedposition) and a position moved upward from the closed position (see FIG.6 , hereinafter, this position is referred to as an open position). Theclosed position is a position (third position) where the rotation guide141 covers the reading unit 110 as viewed from above, and the openposition is a position (fourth position) where the rotation guide 141exposes the reading unit 110 to the outside as viewed from above. Therotation guide 141 is held at the closed position by engaging a fixingportion 141 d, provided at a free end portion thereof, with a conveyingguide 142 fixed to the ADF main body 10B.

In a state in which the rotation guide 141 is positioned at the closedposition, the pressing surface 141 a of the rotation guide 141 contactsthe resin cover 114 a of the pressing portion 114. Then, by elasticityof the compression spring 114 b generated by pressing of the resin cover114 a, the reading unit 110 is pressed toward the shading plate 144. Bythis, a position of the reading unit 110 with respect to the sheetthickness direction D2 is stabilized, so that this contributes toreading of the image information with high accuracy.

The reading unit 110 includes a shaft portion 113 rotatably supported bythe frame of the ADF 10, and is rotatable about another rotational axisA2 (third rotational axis) different from the rotational axis A1 of therotation guide 141. Incidentally, the supporting portion is not limitedto the shaft portion 113 when the supporting portion is capable ofsupporting the reading unit 110, and the read frame 119 may be providedwith a hole (bearing portion) with which a shaft-shaped portion providedto the frame of the ADF 10 is engageable. The reading unit 110 isrotatable between a position where the image information is readablefrom the original fed along the original conveying passage P1 (see FIG.2 , hereinafter, this position is referred to as a reading position) anda position where the glass 111 is exposed to the outside (see FIG. 6 ,hereinafter, this position is referred to as a maintenance position).The reading position is a position (first position) of the reading unit110 where the glass 111 which is a transparent member is in a stateopposing the original conveying passage P1, and the maintenance positionis a position (second position) of the reading unit 110 where the glass111 is in an exposed state as viewed from the outside of the ADF 10.

In a state in which the reading unit 110 is positioned at the readingposition, the glass 111 opposes the shading plate 144 or the baseconveying guide 143 through the original conveying passage P1 and ishidden behind the reading frame 119 as viewed from above with respect tothe vertical direction. The maintenance position is a position of thereading unit 110 where at least a part (preferably a range encompassinga reading range of the CIS 112 or entirety of the glass 111 is exposedto the outside when the ADF 10 is viewed in a predetermined direction(for example, from above with respect to the vertical direction).

The shaft portion 113 is provided so as to project from opposite endportions of the reading frame 119 toward the outside in the X-direction(longitudinal direction), and is held by a holding portion B1 provided.Accordingly, the rotational axis A1 of the rotation guide 141 and therotational axis of the reading unit 110 is substantially parallel toeach other and substantially extend in the X-direction. The holdingportion B1 is a recessed portion (opening) rotatably holding the shaftportion 113, and the holding portion B1 in this embodiment is anelongated circular hole (groove portion) extending in the sheetthickness direction D2. The holding portion B1 as the elongated circularhole is, for example, provided on a side plate (plate-like memberextending in the Y-direction and the Z-direction on a side out of anoriginal passing region with respect to the X-direction) constitutingthe frame of the ADF 10.

The rotational axis A1 of the rotation guide 141 is provided at an endportion of the rotation guide 141 on one end side (right-hand side ofFIG. 2 ) with respect to the Y-direction, and on the other hand, theshaft portion 113 in this embodiment is provided at an end portion ofthe reading unit 110 on the other end side (left-hand side of FIG. 2 )with respect to the Y-direction and on an upper side with respect to theZ-direction. For this reason, the reading unit 110 is rotatedcounterclockwise (in a first rotational direction) in FIG. 2 from thereading position toward the maintenance position, and on the other hand,the rotation guide 141 is rotated clockwise (in a second rotationaldirection) in FIG. 2 from the closed position toward the open position.Thus, when a constitution in which the rotational direction of therotation guide 141 and the rotational direction of the reading unit 110are opposite to each other is employed, there is also an advantage suchthat a rotation range of the reading unit 110 is easily ensured withoutbeing influenced by the rotation guide 141 in the open position.Incidentally, the rotational direction of the rotation guide 141 duringthe open thereof is opposite to a rotational direction of the upperportion cover 147.

Next, the arm 131 will be described. The arm 131 is a member which isrotatably supported by the frame of the ADF 10 and which moves thereading unit 110 from the reading position to the maintenance positionby being rotated in interrelation with rotation of the rotation guide141 from the closed position to the open position. That is, the arm 131is an example of an interrelating mechanism for moving the reading unit110 in interrelation with the rotation of the rotation guide 141. Thearm 131 in this embodiment is a member which is rotated about therotational axis A1 common to the arm 131 and the rotation guide 141 andwhich is rotatable independently of the rotation guide 141.

As shown in FIG. 5A and FIG. 5B, the rotation guide 141 is provided withan arm contact portion 141 b, and the arm 131 is provided with acontacted portion 131 e to which the arm contact portion 141 b iscontactable. In a state in which the rotation guide 141 is positioned inthe closed position and the reading unit 110 is positioned in thereading position, the arm contact portion 141 b is spaced from thecontacted portion 131 e. Further, on a free end side of the arm 131, arcprofiles 131 a, 131 b and 131 c as contact portions for urging(pressing) the reading unit 110. Details of the arc profiles 131 a, 131b and 131 c will be described later.

In this embodiment, a constitution in which the arm 131 is interrelatedwith the rotation guide 141 only within an integral range and in which arotation range of the arm 131 is narrower than a rotation range of therotation guide 141 is employed. Specifically, at the closed position ofthe rotation guide 141, the arm contact portion 141 b of the rotationguide 141 does not contact the arm 131, and at an intermediary positionduring rotation of the rotation guide 141 toward the open position, thearm contact portion 141 b contacts the arm 131 (FIG. 5A, FIG. 5B). Forthis reason, compared with the case where the arm 131 is rotatedintegrally with the rotation guide 141, a rotation locus of the arm 131becomes small, so that a space required for disposing the arm 131therein can be made small.

An operation in which the reading unit 110 is moved from the readingposition to the maintenance position when a maintenance operation isperformed will be described. Incidentally, an operator (user ormaintenance person) opens the upper portion cover 147 in advance byrotating the upper portion cover 147 upward from the closed positionshown in FIG. 1B.

First, in the state shown in FIG. 2 , in order to ensure a rotationspace of the reading unit 110, the operator holds the rotation guide 141and then rotates the rotation guide 141 about the rotational axis A1 inthe clockwise direction in FIG. 2 . Thus, as shown in FIG. 5A, not onlythe rotation guide 141 is spaced upward from the reading unit 110 butalso the arm contact portion 141 b approaches the contacted portion 131e of the arm 131.

When the rotation guide 141 is further rotated, as shown in FIG. 5B, thearm contact portion 141 b contacts the contacted portion 131 e of thearm 131, so that the arm 131 is rotated about the rotational axis 1A inthe clockwise direction in FIG. 5B. By the rotation of the arm 131, thearc profiles 131 a and 131 c provided on the free end side of the arm131 contact and urge (press) the reading unit 110, and thus rotate thereading unit 110 about the shaft portion 113 in the counterclockwisedirection in FIG. 5B.

By this, the reading unit 110 is moved from the reading position shownin FIG. 2 to the maintenance position shown in FIG. 6 .

The operator is capable of easily performing an operation such ascleaning of the glass 111 or the like for the reading unit 110 moved tothe maintenance position. The rotation guide 141 can be constituted sothat the reading unit 110 is held at the maintenance position throughthe arm 131 by being retained at the open position, for example, by aself-weight thereof. Incidentally, as described later specifically, whenthe reading unit 110 reaches the maintenance position, the pressingportion 114 of the reading unit 110 abuts against an abutment surface142 a (FIG. 6 ) of the conveying guide 142 fixed to the frame of the ADFmain body 10A.

When the operation such as the cleaning of the glass 111 or the like isended, in the state of FIG. 6 , the operator rotates the rotation guide141 in the counterclockwise direction in FIG. 6 from the open positiontoward the closed position. Then, the arm 131 is rotated in thecounterclockwise direction in FIG. 6 with the rotation of the rotationguide 141. Further, the reading unit 110 is rotated in the clockwisedirection in FIG. 6 from the maintenance position toward the readingposition while being supported by the arm 131. Then, when the rotationalguide 141 reaches the closed position, the reading unit 110 is returnedto the state of FIG. 2 in which the reading unit 110 is held at thereading position. That is, in this embodiment, the reading unit 110 ismoved from the reading position to the maintenance position ininterrelation with the opening operation of the rotation guide 141, andis moved from the maintenance position to the reading position ininterrelation with the closing operation of the rotation guide 141.

Thus, the reading unit 110 is constituted so as to be rotatable aboutthe rotational axis different from the rotational axis of the rotationguide 141, so that when the reading unit 110 is moved for performing thecleaning of the glass 111 or the jam clearance, the impact exerted onthe reading unit 110 can be reduced.

Further, in this embodiment, the holding portion B1 on a mating side(frame side of the ADF 10) to the shaft portion 113 of the reading unit110 is constituted as the elongated circular hole extending in the sheetthickness direction. In order to make the reading unit 110 rotatableseparately from the rotation guide 141, the holding portion B1 may alsobe constituted as a cylindrical hole corresponding to the shaft portion113. However, in this embodiment, the holding portion B1 is constitutedas the elongated circular hole, so that in addition to rotation of thereading unit 110, movement of the reading unit 110 in the sheetthickness direction D2 is allowed. By this, while regulating apositional deviation of the reading unit 110 in the sheet feedingdirection D1, a variation in position of the reading unit 110 due to apart tolerance or the like of the ADF 10 can be absorbed by movement ofthe shaft portion 113. The variation in position of the reading unit 110is absorbed, so that the glass 111 can be more stably positionedrelative to the shading plate 144 through the gap sheet 115.

Further, as indicated by an arrow in FIG. 6 , in a state in which thereading unit 110 is rotated to the maintenance position, correspondingto a length of the holding portion B1, the reading unit 110 can beraised, and therefore, an operation property such as a maintenanceproperty can be improved. At this time, when the abutment surface 142 aof the conveying guide 142 is constituted as an inclined surface withinclination along the holding portion B1, the abutment surface 142 aalso functions as a guide when the reading unit 110 is raised.Incidentally, in this embodiment, a constitution in which thelongitudinal direction of the elongated circular hole which is theholding portion B1 substantially coincides with the sheet thicknessdirection D2 of the reading unit 110 at the reading position wasemployed. The holding portion B1 is not limited thereto, but may also bean elongated circular hole extending in a direction, different from thesheet thickness direction D2, within directions crossing the sheetfeeding direction D1 as viewed in the X-direction.

[Wiring to Reading Unit]

Next, a wiring path to the reading unit 110 and an advantage thereof inthis embodiment will be described.

As described above, the reading unit 110 is electrically connected tothe controller 2C (FIG. 1B) of the original reading apparatus 2 throughthe electric wire 150. The electric wire 150 is not only a signal linefor transmitting, to the controller 2C, the image information read bythe reading unit 110 but also an electric power line for supplyingelectric power to the reading unit 110. In this embodiment, as theelectric wire 150, a flexible flat cable (FFC) is used.

As shown in FIGS. 2 and 3 , the electric wire 150 is connected to thesensor substrate 112 c inside the reading unit 110 and is led out to theoutside of the reading unit 110 through an opening (outlet 146) providedin the reading frame 119. On the outside side of the reading unit 110,the electric wire 150 is wired inside the ADF main body 10A while beingguided by a guiding member mounted on the frame of the ADF 10 and isconnected to the controller 2C of the scanner portion 20. Accordingly,the electric wire 150 includes an inner unit portion 150 a held in thereading unit 110, a main body-side portion 150 b held by the frame ofthe ADF main body 10A, and an intermediary portion 150C connecting theinner unit portion 150 a and the main body-side portion 150 b. Theintermediary portion 150 c is a portion between the outlet 146 of thereading unit 110 and an inlet 149 (opening for receiving the electricwire 150 or guiding member for holding the electric wire 150) on the ADFmain body 10A. Incidentally, in order to facilitate flexure of theintermediary portion 150 c, the electric wire (FFC) 150 is disposed sothat a widthwise direction of the electric wire 150 in the intermediaryportion 150 c is substantially parallel to the X-direction which is amain scan direction of the reading unit 110.

When the reading unit 110 which is a movable member relative to theframe of the ADF main body 10A is moved, the electric wire 150 isflexed, so that movement of the reading unit 110 is allowed. That is,when the reading unit 110 is rotated from a reading position shown inFIG. 17A to a maintenance position shown in FIG. 17B, principally theintermediary portion 150 c of the electric wire 150 is flexed byfollowing a change in attitude of the reading unit 110, so that therotation of the reading unit 110 is allowed. Further, as shown in FIG.17C<when the reading unit 110 positioned in the maintenance position israised along the holding portion B1, the intermediary portion 150 c ofthe electric wire 150 extends (by which flexure due to an excessivelength is eliminated), so that upward movement of the reading unit 110is allowed.

Here, in this embodiment, by employing a constitution in which thereading unit 110 is rotatable separately form the rotation guide 141,stress exerted on the electric wire 150 when the reading unit 110 isrotated can be reduced. This will be described below.

As shown in FIG. 3 , the electric wire 150 is led out from an inside toan outside the reading unit 110 through the neighborhood of therotational axis A2 of the reading unit 110. As viewed in theX-direction, a distance from the reading unit 110 to the outlet 146through which the electric wire 150 is led out is shorter than at leasta distance from the rotational axis A1 (second rotational axis) of therotation guide to the outlet 146. For that reason, compared with thecase where the reading unit 110 is mounted on the rotation guide 141, amovement amount of the outlet 146 when the reading unit 110 is rotatedbecomes small. Further, the neighborhood of the rotational axis A2 maypreferably refers specifically to the case where the electric wire 150passes through a position of the rotational axis A2 overlaps with theshaft portion 113 in a state in which these portions are viewed in theX-direction. Further, an arrangement such that of four corner portionsof the reading frame 119 having a substantially rectangular shape asviewed in the X-direction, one corner portion closest to the outlet 146through which the electric wire 150 is led out and one corner portionclosest to the shaft portion 113 are the same is suitable.

Thus, in the case where the electric wire 150 is wired through theneighborhood of the rotational axis A2 of the reading unit 110, when thereading unit 110 is rotated about the rotational axis A2, the electricwire 150 is flexed principally in the neighborhood of the rotationalaxis A2 (see FIG. 17B). That is, the electric wire 150 is flexed so thatthe inner unit portion 150 a of the electric wire 150 is rotated aboutthe neighborhood of the rotational axis A2 as a supporting point. Forthat reason, a fluctuation in distance from the outlet 146 of theelectric wire 150 on the reading unit 110 side to the inlet 149 of theelectric wire 150 on the ADF main body 10A side is small. When thisfluctuation is large, there is a liability that the electric wire 150 isbroken or disconnected by tension. For that reason, it would beconsidered that an excessive length of the intermediary portion 150 c isincreased by taking a fluctuation amount into consideration, but whenthe excessive length of the intermediary portion 150 c is increased,this increase leads to an increase in cost and upsizing of theapparatus. On the other hand, in this embodiment, the fluctuation amountof the distance from the outlet of the electric wire 150 on the readingunit 110 side to the inlet of the electric wire 150 on the ADF main body10A side is small, and therefore, even when the excessive length of theintermediary portion 150 c is set at a small value, breakage or the likedoes not readily occur, so that the increase in cost and upsizing of theapparatus can be prevented.

Incidentally, in the case where a constitution in which the reading unit110 is rotated integrally with the rotation guide 141 is employed,wiring of the electric wire 150 through the neighborhood of therotational axis A2 becomes difficult. This is attributable to thefollowing circumstances. First, the conveying guide for guiding thesheet, such as the rotation guide 141 is a relatively large memberextending along the sheet conveying passage. For that reason, when sucha large member is intended to be rotated, it is natural that therotational axis of the conveying guide is disposed in the neighborhoodof an upstream end or a downstream end of the conveying guide withrespect to the feeding direction of the sheet to be guided. On the otherhand, the reading unit is disposed at a position (below the rotationguide 141 in the case of the reading unit 110) apart from the guidingsurface of the conveying guide so as not to prevent the feeding of thesheet, and therefore, it becomes difficult that the outlet of theelectric wire from the reading unit is disposed in the neighborhood ofthe rotational axis of the conveying guide. Further, in the neighborhoodof the conveying guide, the feeding roller for feeding the sheet isdisposed in many cases, so that when the reading unit is intended to bedisposed while avoiding interference with the feeding roller, it becomesfurther difficult that the outlet of the electric wire from the readingunit is disposed in the neighborhood of the rotational axis of theconveying guide. With an increasing distance of the outlet of theelectric wire, from the reading unit, from the rotational axis of theconveying guide, a fluctuation amount of the distance from the outlet ofthe downstream on the reading unit side to the inlet of the electricwire on the ADF main body side when the conveying guide is rotatedbecomes large. As a result, a breakage risk of the electric wire 150arises.

On the other hand, in this embodiment, the reading unit 110 employs amechanism rotatable separately from the rotation guide 141, andtherefore, the electric wire 150 can be wired through the neighborhoodof the rotational axis A2 of the reading unit 110. Further, therotational axis A2 of the reading unit 110 can be disposed below theguiding surface of the rotation guide 141. As a result, as describedabove, the breakage of the electric wire 150 can be made hard to occur.

[Details of Arm]

Next, a constitution in which an operating property when the readingunit 110 is moved while being made rotatable in a wide rotation range iscapable of being improved will be described using FIGS. 7 and 8 .

The reading unit 110 assumes an attitude in the reading position suchthat the glass 111 faces downward with respect to the Z-direction andassumes an attitude in the maintenance position such that the glass 111is exposed to the outside as viewed from above with respect to theZ-direction. That is, in this embodiment, the transparent member facesdownward with respect to the vertical direction in a state in which thereading unit is positioned in the first position and faces upward withrespect to the vertical direction in a state in which the reading unitis positioned in the second position.

When a degree of inclination of the glass 111 relative to the horizontaldirection in the reading position is excessively large, a degree offlexure of the original conveying passage P1 becomes large, so thatfeeding of thick paper or the like becomes difficult, and therefore, anangle of the inclination of the glass 111 is, for example, 45 degrees orless, preferably 30 degrees or less. For that reason, the reading unit110 is constituted so as to be rotatable between the read position andthe maintenance position with a rotation range of, for example, 60degrees or more, preferably 75 degrees or more, more preferably 90degrees or more.

In the case where the reading unit 110 is rotated within such a rotationrange, in a constitution in which an operator directly puts one's handon the reading unit 110, the hand is liable to be caught between therotated reading unit 110 and another portion of the ADF 10, so thatthere was room for improvement in operating property.

As described above, in this embodiment, the free end portion of the arm131 interrelated with the rotation of the rotation guide 141 iscontacted to the reading unit 110 from below, so that the reading unit110 is rotated in interrelation with the rotation guide 141 (see FIGS. 5and 6 ). At this time, the arm 131 is rotated in a rotational directionopposite to the rotational direction of the reading unit 110, so thatthe reading unit 110 is moved from the reading position to themaintenance position while changing a contact position of the arm 131with the reading unit 110. For this reason, the operating property canbe improved while enabling the rotation of the reading unit 110 within awide rotation range.

Further, the reading unit 110 can be made movable from the readingposition to the maintenance position with a small operating force to theextent possible, so that an operation load can be alleviated. In thefollowing, this will be specifically described.

FIG. 7 shows a positional relationship between the reading unit 110, therotational axis A1 of the arm 131, and the rotational axis A2 of thereading unit 110 when the arm 131 is first contacted to the reading unit110. In order to rotate the reading unit 110 in the counterclockwisedirection by the contact of the arm 131 from below, it is efficient tobring the arm 131 into contact with the first contact surface 110 awhich is a surface (where the glass 111 is disposed) on a lower side ofthe reading unit 110 in the reading position.

Then, in order to consider that the arm 131 is contacted at whichposition of the first contact surface 110 a, three points a, b and cwill be considered. A chain double-dashed line passing through each ofthe points is a rotation locus about the rotational axis A1 for anassociated point, and an arrow represents a tangential direction(direction of a load when the reading unit 110 is pressed at theassociated point) thereof.

In the case where the arm 131 is contacted to the reading unit 110 atthe point a, a load direction substantially extends toward therotational axis A2 of the reading unit 110, and therefore, efficiency ispoor for rotating the reading unit 110. In the case where the arm 131 iscontacted to the reading unit 110 at the point c, rather, moment in theclockwise direction in FIG. 7 which is a direction opposite to adirection in which the operator intends to rotate the reading unit 110acts on the reading unit 110. On the other hand, as at the point b, inthe case where the arm 131 is contacted to the reading unit 110 at aposition, on the first contact surface 110 a, apart from the rotationalaxis A2 on a right-hand side in the figure, the reading unit 110 isrotated even when the load required to press the reading unit 110 by thearm 131 is relatively small.

FIG. 8 shows a maximum angle at which the reading unit 110 can berotated by pushing the first contact surface 110 a from below. If thearm 131 is contacted to the first contact surface 110 a at a point d,when the reading unit 110 is rotated to a position where the firstcontact surface 110 a is vertically disposed, at the point d, the arm131 cannot further press the reading unit 110. In order to furtherrotate the reading unit 110, as shown at a point e, a constitution inwhich the arm 131 contacts and presses the reading unit 110 at thesecond contact surface 110 b different from the first contact surface110 a is employed.

In this embodiment, in view of the above, a constitution in which thearm 131 is provided with the two contact portions (131 a, 131 c) and inwhich the two contact portions are successively contacted to the firstcontact surface 110 a and the second contact surface 110 b,respectively, is employed.

In the following, such a constitution will be described. As shown inFIG. 5B, at the free end portion of the arm 131 in this embodiment, thethree arc profiles 131 a, 131 b and 131 c are provided.

From the rotational axis A1 toward an outside with respect to a radialdirection, these arc profiles are referred to as a first arc profile 131a, a second arc profile 131 b, and a third arc profile 131 c. The firstarc profile 131 a and the third arc profile 131 b are arcuately curvedsurfaces which are each projected toward a downstream side of therotational direction (the clockwise direction in FIG. 5B) of the arm 131when the arm 131 presses the reading unit 110. The first arc profile 131a is a first projection for pressing the first contact surface 110 a(first surface) of the reading unit 110. The third arc profile 131 c isa third projection for pressing the second contact surface 110 b (secondsurface) of the reading unit 110. The second arc profile 131 b is anarcuately curved surface which is concaved between the first arc profile131 a and the third arc profile 131 c and which forms a space forreceiving a corner portion 110 c between the first contact surface 110 aand the second contact surface 110 a. Incidentally, in this embodiment,the first contact surface 110 a and the second contact surface 110 c areadjacent two surfaces (surfaces crossing perpendicularly each other) ofthe reading unit 110 which has a substantially rectangular shape asviewed in the X-direction, but surfaces extending in directions crossingeach other at an angle different from a right angle may be the firstsurface and the second surface, respectively.

In this embodiment, the first contact surface 110 a of the reading unit110 is a surface of the glass sheet 115 (gap forming member) sticked tothe glass 111. The arm 131 is prevented from directly contacting theglass 111, whereby a possibility that the glass 111 is changed isreduced. Incidentally, as shown in FIG. 4 , a contact position of thearm 131 with the gap sheet 115 is deviated from an abutment region ofthe shading plate 144 against the gap sheet 115 in the X-direction. Forthat reason, even when the surface of the first contact surface 110 a ofthe gap sheet 115 to which the arm 131 is repetitively contacted isroughened, accuracy of a gap width (range) formed between the glass 111and the shading plate 144 is not lowered.

As shown in FIG. 5B, when the arm 131 is rotated in interrelation withthe rotation of the rotation guide 141, first, the first arc profile 131a contacts the first contact surface 110 a of the reading unit 110 andcauses the reading unit 110 to start to rotate from the readingposition. At this time, the third arc profile 131 c does not contact thesecond contact surface 110 b of the reading unit 110.

When the arm 131 is further rotated and thus an angle of the readingunit 110 reaches a predetermined angle, the third arc profile 131 ccontacts the second contact surface 110 b, and the first arc profile 131a is separated from the first contact surface 110 a. Then, the third arcprofile 131 c presses the second contact surface 110 b, so that as shownin FIG. 6 , the reading unit 110 is rotated to the maintenance position.

When the reading unit 110 reaches the maintenance position, as shown inFIG. 6 , the pressing portion 114 of the reading unit 110 abuts againstthe abutment surface 142 a of the conveying guide 142 fixed to the frameof the ADF main body 10A. At this time, by elasticity of the elasticmember (compression spring 114 b) provided on the pressing portion 114,an impact of abutment of the reading unit 110 against the conveyingguide 142 is alleviated. That is, the pressing portion 114 performs notonly positioning action on the reading unit 110 during the image readingbut also a function of a buffer when the reading unit 110 is moved tothe maintenance position.

Thus, a constitution in which the contact position between the arm 131and the reading unit 110 is switched depending on the rotation angle ofthe reading unit 110 is employed, so that while the reading unit 110 ismade rotatable in the wide rotation range, an operation load can bealleviated. Further, a recessed arc profile 131 c is provided betweenthe two projections of the arm 131 contacting the first contact surface110 a and the second contact surface 110 b of the reading unit 110, andtherefore, the arm 131 and the reading unit 110 are not put in a lockedstate by the two projections. That is, the corner portion 110 c betweenthe first contact surface 110 a and the second contact surface 110 b isaccommodated in a space inside the arc profile 131 c, so that the statebetween the arm 131 and the reading unit 110 is smoothly shifted from acontact state between the first arc profile 131 a and the first contactsurface 110 a to a contact state between the third arc profile 131 c andthe second contact surface 110 b.

Further, in this embodiment, the three arc profiles 131 a, 131 b and 131c are smoothly connected to each other (i.e., a tangential direction isnot changed discontinuously), and therefore, even when the contactposition of the reading unit 110 is switched between the respectiveprofiles, smooth rotation can be realized.

Incidentally, in this embodiment, the case where each of the twoprojections and the recess between the two projections is constituted bythe arcuate curves was described, but these portions may also beconstituted as curves other than the arcuate curves.

Modified Embodiment 1

In the embodiment 1, the constitution in which the reading unit 110 isrotated in interrelation with opening and closing of the rotation guide141 through the arm 131 moved in interrelation with the opening andclosing of the rotation guide 141 was described. The present inventionis not limited thereto, and a constitution as shown in FIG. 9 in whichthe arm 131 is not provided and in which the operator directly rotatesthe reading unit 110 by one's hand(s) may be employed. In this case, inorder to move the reading unit 110 to the maintenance position, theoperator first rotates the rotation guide 141 from the closed positionto the open position while holding the rotation guide 141, and thenrotates the reading unit 110 from the reading position to themaintenance position while holding the reading unit 110.

Modified Embodiment 2

Further, as another constitution in which the reading unit 110 isrotated in interrelation with the opening and closing of the rotationguide 141, a constitution in which a part of the rotation guide 141 iscontacted to the reading unit 110 in a manner such that the arm 131 isformed integrally with the rotation guide 141 may be employed.Incidentally, in the embodiment 1, the constitution in which the arm 131is rotatable relative to the rotation guide 141 and in which therotation range of the arm 131 is narrower than the rotation range of therotation guide 141 is employed, and therefore, as described above,downsizing of the apparatus can be realized compared with this modifiedembodiment.

Modified Embodiment 3

In the embodiment 1, the case where the arm 131 is disposed on one sideof the reading unit 110 and the rotation guide 141 with respect to theX-direction was described, but the arm 131 may be disposed on each ofopposite sides with respect to the X-direction. In that case, atorsional load is not readily exerted on the reading unit 110 and therotation guide 141.

Embodiment 2

An embodiment 2 will be described using FIGS. 10 to 12 . This embodimentis different from the embodiment 1 in that a constitution in which in astate in which the rotation guide 141 is moved to the open position inadvance, the operator holds and operates the operating portion of thearm 131 and thus rotates the reading unit 110 is employed. In thefollowing, elements represented by reference numerals or symbols commonto the embodiments 1 and 2 are regarded as those having substantiallythe same constitutions and functions, and an element different fromthose in the embodiment 1 will be principally described.

As shown in FIG. 10 , the arm 131 in this embodiment is provided with anarm operating portion 131 d as an operating portion (lever, handle). Thearm operating portion 131 d is disposed, for example, so as to projectupward from the guiding surface of the rotation guide 141 on a frontside of the image forming apparatus 1 relative to the rotation guide 141in order to facilitate access by the operator in a state in which theupper portion cover 147 is opened. The arm operating portion 131 d willbe described as being rotated integrally with another portion of the arm131, but may be connected rotatably relative to the aforementionedanother portion so as to be interrelated with the aforementioned anotherportion only in a predetermined rotation range.

In the case where the reading unit 110 is moved from the readingposition to the maintenance position during a maintenance operation, theoperator opens the upper portion cover 147 in advance, and then movesthe rotation guide 141 to the open position. In this state, the operatorputs one's hand on the arm operating portion 131 a and rotates the arm131 in the clockwise direction in FIG. 10 .

Then, as shown in FIGS. 11 and 12 , the arc profiles 131 a and 131 cprovided on the free end portion side of the arm 131 contacts andpresses the reading unit 110 and rotates the reading unit 110 about theshaft 113 in the counterclockwise direction in the figures. By this, thereading unit 110 is moved from the reading position shown in FIG. 10 tothe maintenance position shown in FIG. 11 . Thus, the reading unit 110is constituted so as to be rotatable independently of the rotation guide141, so that it is possible to reduce impact received by the readingunit 110 when the reading unit 110 is moved when cleaning of the glass111 or the jam clearance is performed.

Further, in a process in which the arm 131 is rotated, similarly as inthe embodiment 1, to two arc profiles 131 a and 131 c provided on thearm 131 successively contact the first contact surface 110 a and thesecond contact surface 110 b. At this time, the operator may only berequired to operate the arm operating portion 131 d in the case wherethe reading unit 110 is moved to the maintenance position, so that apossibility that the operator's hand is caught between the reading unit110 and ADF main body 10A is low. Accordingly, the operating propertycan be improved while making the reading unit 110 rotatable within awide rotation range.

Incidentally, also in this embodiment, the reading unit 110 isconstituted so as to be rotatable independently of the rotation guide141, so that a breakage risk of the electric wire 150 when the readingunit 110 is rotated is capable of being reduced.

Embodiment 3

An embodiment 3 will be described using FIGS. 13 and 14 . Thisembodiment is different from the embodiment 1 in that in position of arotational axis of the reading unit 110 and a rotational direction ofthe reading unit 110 are different from those in the embodiment 1. Inthe following, elements represented by reference numerals or symbolscommon to the embodiments 1 and 3 are regarded as those havingsubstantially the same constitutions and functions, and an elementdifferent from those in the embodiment 1 will be principally described.

As shown in FIG. 13 , the reading unit 110 includes the shaft portion113 and is rotatable about a rotational axis A3 (second rotational axis)different from the rotational axis A1 of the rotation guide 141 as theconveying guide. In this embodiment, the rotational axis A3 of thereading unit 110 is provided on one side of the Y-direction of thereading unit 110 (negative side of the Y-direction) and at an endportion on an upper side of the Z-direction. That is, in thisembodiment, the first rotational axis is provided at an upstream-sideend portion of the conveying guide with respect to the sheet feedingdirection (leftward direction in FIG. 13 ) of the sheet guided by theconveying guide. The second rotational axis is provided at the openposition-side end portion of the reading unit with respect to the sheetfeeding direction of the sheet guided by the conveying guide.

For this reason, the rotation guide 141 is rotated clockwise about therotational axis A1 from the closed position toward the open position,and the reading unit 110 is rotated clockwise about the rotational axisA3 from the reading position to the maintenance position. Thus, even ina constitution in which the rotational directions of the rotation guide141 and the reading unit 110 when the glass 111 as the transparentmember is exposed to the outside are the same, it is possible to achieveeffects similar to the effects of the embodiments 1 and 2. Whether therotational directions of the rotation guide 141 and the reading unit 110are made the same direction or different directions is selecteddepending on a specific constitution of the ADF 10, such as a positionalrelationship of these members with members provided at a periphery ofthese members, or the like.

Incidentally, in this embodiment, the position of the rotational axis A3of the reading unit 110 is different from those in the embodiments 1 and2, and therefore, it is preferable that a wiring path of the electricwire 150 connected to the reading unit 110 is also changed from those inthe embodiments 1 and 2. As shown in FIG. 13 , the electric wire 150 isled out from the inside to the outside of the reading unit 110 throughthe neighborhood of the rotational axis A3 of the reading unit 110. Atthis time, the electric wire 150 is different from the electric wire 150in the embodiment 1, and is led out to the negative side of theY-direction (downstream side of the sheet feeding direction in thereading position) and then is guided and wired by a guiding member 152provided on the frame of the ADF main body 10A.

A distance from the rotational axis A3 of the reading unit 110 to anoutlet where the electric wire 150 is led out from the reading unit 110is shorter than at least a distance from the rotational axis A1 of therotation guide 141 to the outlet. Further, the neighborhood of therotational axis A3 is suitable when the electric wire 150 passes througha position where the rotational axis A3 overlaps with the shaft portion113 in a state in which the rotational axis A3 is viewed specifically inthe X-direction. Further, it is suitable that of four corner portions ofthe reading frame 119 which has a substantially rectangular shape asviewed in the X-direction, one corner portion is closest to the outletthrough which the electric wire 150 is led out and is closest to theshaft portion 113.

Thus, in the case where the electric wire 150 is wired through theneighborhood of the rotational axis A3 of the reading unit 110, when thereading unit 110 is rotated about the rotational axis A3, the electricwire 150 is principally flexed in the neighborhood of the rotationalaxis A3 (see FIG. 13 ). For that reason, a fluctuation in distance fromthe outlet of the electric wire 150 on the reading unit 110 side to theinlet 149 (opening through which the electric wire 150 is received or aguiding member for holding the electric wire 150) of the electric wire150 on the ADF main body 10A side is small. Accordingly, even in theconstitution of this embodiment, it is possible to reduce a possibilityof breakage of the electric wire 150.

Embodiment 4

An embodiment 4 will be described using FIG. 15 . This embodiment isdifferent from the embodiment 2 in position of the rotational axis ofthe rotation guide 141 and the rotational direction of the rotationguide 141. In the following, elements represented by reference numeralsor symbols common to the embodiments 2 and 4 are regarded as thosehaving substantially the same constitutions and functions, and anelement different from those in the embodiment 2 will be principallydescribed.

As shown in FIG. 15 , the rotation guide 141 as the conveying guide isprovided rotatably about a rotational axis A4 (first rotational axis).The rotational axis A1 is provided at an end portion of the rotationguide 141 on a downstream side (left-hand side in FIG. 15 , positiveside of the Y-direction) with respect to the sheet feeding direction ofthe sheet guided by the rotation guide 141. That is, in this embodiment,the first rotational axis is provided at the downstream-side end portionof the conveying guide with respect to the sheet feeding direction ofthe sheet guided by the conveying guide. The second rotational axis isprovided at a downstream-side end portion of the reading unit withrespect to the sheet feeding direction of the sheet guided by therotation guide.

For this reason, the rotation guide 141 is rotated counterclockwiseabout the rotational axis A4 in FIG. 15 from the closed position towardthe open position, and the reading unit 110 is rotated counterclockwiseabout the rotational axis A2 in FIG. 15 from the reading position towardthe maintenance position. Even in such a constitution, it is possible toobtain effects similar to the effects of the embodiments 1 and 2.

Modified Embodiment

A modified embodiment will be described using FIG. 16 . In this modifiedembodiment, the position of the rotational axis A4 of the rotation guide141 and the rotational direction of the rotation guide 141 in theembodiment 4, and the position of the rotational axis A3 of the readingunit 110 and the rotational direction of the reading unit 110 in theembodiment 3 are combined with each other. That is, in this modifiedembodiment, the first rotational axis is provided at the downstream-sideend portion of the conveying guide with respect to the sheet feedingdirection of the sheet guided by the conveying guide. The secondrotational axis is provided at the upstream-side end portion of thereading unit with respect to the sheet feeding direction of the sheetguided by the conveying guide.

For this reason, the rotation guide 141 is rotated counterclockwiseabout the rotational axis A4 in FIG. 16 from the closed position towardthe open position and the reading unit 110 is rotated clockwise aboutthe rotational axis A3 in FIG. 16 from the reading position toward themaintenance position. Even in such a constitution, it is possible toobtain effects similar to the effects of the embodiments 1 and 2.

Embodiment 5

An embodiment 5 will be described using FIGS. 18 and 19 . Thisembodiment is different from the embodiment 2 in that a plurality of armmembers are contacted to the first contact surface and the secondcontact surface of the reading unit. In the following, elementsrepresented by reference numerals or symbols common to the embodiments 2and 5 are regarded as those having substantially the same constitutionsand functions, and an element different from those in the embodiment 2will be principally described.

The ADF 10 in this embodiment includes an arm 132 as a first arm memberand an arm 133 as a second arm. The arms 132 and 133 are rotatablysupported by the frame of the ADF main body 10A and are rotated aboutthe rotational axis A1. The arms 132 and 133 overlap with each other asviewed in the X-direction. Further, the arms 132 and 133 can be rotatedby operating the arm operating portion 131 d. Even in such aconstitution, an effect similar to the effect of the embodiment 1 can beachieved.

In the case where the arm operating portion 131 d is rotated in theclockwise direction from a state of FIG. 18 , first, the arm 132 isrotated and contacted to the first contact surface 110 a of the readingunit 110. Then, at the time when the arm 132 is rotated by apredetermined angle, the arm 133 starts rotation and is contacted to thesecond contact surface 110 b of the reading unit 110. By this, as shownin FIG. 19 , the reading unit 110 is rotated to the maintenanceposition. Thus, the arms 132 and 133 press a plurality of surfaces ofthe reading unit 110, so that it is possible to realize rotation of thereading unit 110 in a wide rotation range. Further, by employing aconstitution in which the two arms 132 and 133 which overlap with eachother are interrelated with each other with a time difference, it ispossible to reduce a space necessary to arrange the arms 132 and 133.

Embodiment 6

An embodiment 6 will be described using FIGS. 20 and 21 . Thisembodiment is different from the embodiment 2 in that a readingunit-side contact surface to which the arm member is contacted is made acurved surface and thus a rotation range of the reading unit is ensured.In the following, elements represented by reference numerals or symbolscommon to the embodiments 2 and 6 are regarded as those havingsubstantially the same constitutions and functions, and an elementdifferent from those in the embodiment 2 will be principally described.

As shown in FIG. 20 , the reading unit 110 in this embodiment includesan arm contact surface 110 d different from the surface on which theglass 111 is disposed. The arm contact surface 110 d is substantiallyarcuate curved surface which projects toward an upstream side of therotational direction (downstream direction in FIG. 20 ) of the arm 131in a state in which the arm contact surface 110 d is viewed in theX-direction. On the other hand, a free end of the arm 131 is formed in asubstantially linear shape along a rectilinear line passing through therotational axis A1. The arm contact surface 110 d is the curved surfacewhich is substantially continuous at least between a first contact pointd1 (FIG. 20 ) and a second contact point d2 (FIG. 21 ).

The first contact point d1 is a position where the reading unit 110 iscontacted to the arm 131 in a state in which the reading unit 110 ispositioned in the reading position. The second contact point d2 is aposition where the reading unit 110 is contacted to the arm 131 in astate in which the reading unit 110 is positioned in the maintenanceposition.

When the arm 131 is rotated in the clockwise direction in FIG. 20 , thearm 131 rotates the reading unit 110 from the reading position to themaintenance position while continuously changing a contact position tothe arm contact surface 110 d from the first contact point d1 to thesecond contact point d2. Therefore, according to the constitution ofthis embodiment, even when the arm 131 is formed in a simple shape, aneffect similar to the effect of the embodiment 2 can be obtained, sothat a degree of design freedom can be enlarged.

OTHER EMBODIMENTS

In the above-described embodiments, the constitution in which thepresent invention is applied to the image reading apparatus installed atan upper portion of the apparatus main assembly of the image formingapparatus was described. The present invention is not limited thereto,and is also applicable to an image reading apparatus which isindependent of an image forming apparatus.

According to the present invention, it is possible to facilitatecleaning of the glass surface of the reading unit.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2021-105488 filed on Jun. 25, 2021, which is hereby incorporated byreference herein in its entirety.

1. An image reading apparatus for reading image information from asheet, comprising: a cover unit provided rotatably about a firstrotational axis and including an upper surface of said image readingapparatus; a sheet conveying member configured to convey the sheet alonga sheet conveying passage; a conveying guide provided rotatably about asecond rotational axis different from the first rotational axis andconfigured to guide the sheet fed by said sheet conveying member; and areading unit which includes a transparent member and a reading portionconfigured to read, through said transparent member, an image on thesheet fed by said sheet conveying member and which is provided rotatablyabout a third rotational axis different from the first rotational axisand the second rotational axis, wherein said cover unit is rotatablebetween a closed position where said cover unit forms the sheetconveying passage in cooperation with said conveying guide and an openposition where the sheet conveying passage is open, and wherein in astate in which said cover unit is positioned in the open position, saidtransparent member is exposed to an outside of said image readingapparatus by rotation of said conveying guide and said reading unit. 2.An image reading apparatus according to claim 1, further comprising anarm member configured to move said reading unit, in contact with saidreading unit, from a first position where said transparent memberopposes the sheet conveying passage to a second position where saidtransparent member is exposed to the outside of said image readingapparatus.
 3. An image reading apparatus according to claim 2, whereinsaid conveying guide is rotatable between a third position where saidconveying guide covers said reading unit and a fourth position wheresaid reading unit is exposed to the outside as viewed from above, andwherein said arm member is configured to move said reading unit from thefirst position to the second position in interrelation with rotation ofsaid conveying guide from the third position to the fourth position. 4.An image reading apparatus according to claim 2, wherein said conveyingguide is rotatable between a third position where said conveying guidecovers said reading unit and a fourth position where said reading unitis exposed to the outside as viewed from above, and wherein said armmember includes an operating portion for performing an operation inwhich said reading unit is moved from the first position to the secondposition by said arm member in a state in which said conveying guide isrotated from the third position to the fourth position.
 5. An imagereading apparatus according to claim 2, wherein said reading unit isrotated in a first rotational direction about the third rotational axisfrom the first position to the second position, and wherein said armmember is rotatable about the second rotational axis in a secondrotational direction opposite to the first rotational direction so as torotate said reading unit from the first position to the second positionwhile changing a contact position thereof with said reading unit.
 6. Animage reading apparatus according to claim 5, wherein said reading unitincludes a first surface on which said transparent member is providedand a second surface extending in a direction crossing the first surfaceas viewed in a sheet widthwise direction, wherein said arm memberincludes a first projection for urging the first surface and a secondprojection contactable to the second surface, wherein in a case thatsaid arm member is rotated in the second rotational direction, saidsecond projection contacts the second surface after first projectioncontacts the first surface.
 7. An image reading apparatus according toclaim 5, wherein said arm member is a first arm member, wherein saidimage reading apparatus further comprises a second arm member configuredto move said reading unit from the first position to the second positionin contact with said reading unit, wherein said reading unit includes afirst surface on which said transparent member is provided and a secondsurface extending in a direction crossing the first surface as viewed ina surface widthwise direction, and wherein in a case that said first armmember and said second arm member are rotated in the second rotationaldirection, said second arm member contacts the second surface after saidfirst arm member contacts the first surface.
 8. An image readingapparatus according to claim 5, wherein said reading unit includes acurved surface curved as viewed in a sheet widthwise direction, andwherein in a case that said arm member is rotated in the secondrotational direction, a contact position between said arm member and thecurved surface continuously changes.
 9. An image reading apparatusaccording to claim 2, further comprising: an opposing member opposingsaid transparent member; and a gap forming member mounted on saidtransparent member and configured to form a gap between said transparentmember and said opposing member in contact with said opposing member sothat the sheet passes through the gap, wherein said arm member contactssaid gap forming member.
 10. An image reading apparatus according toclaim 1, wherein said reading unit is rotatable between a first positionwhere said transparent member opposes the sheet conveying passage and asecond position where said transparent member is exposed to the outsideof said image reading apparatus, wherein in a state in which saidreading unit is positioned in the first position, said transparentmember faces downward in a vertical direction, and wherein in a state inwhich said reading unit is positioned in the second position, saidtransparent member faces upward in the vertical direction.
 11. An imagereading apparatus according to claim 1, wherein said reading unit isrotatable between a first position where said transparent member opposesthe sheet conveying passage and a second position where said transparentmember is exposed to the outside of said image reading apparatus,wherein said reading unit further includes a pressing portion includingan elastic member and a contacted portion to which said conveying guideis contactable, and is positioned in the first position by elasticity ofsaid elastic member through urging of said conveying guide against saidcontacted portion, and wherein in a case that said reading unit is movedfrom the first position to the second position, said reading unit isbuffered by the elasticity of said elastic member through contact ofsaid contacted portion with a member fixed on a frame of said imagereading apparatus.
 12. An image reading apparatus according to claim 1,further comprising a frame, wherein said reading unit includes a shaftportion provided on the third rotational axis, wherein said frameincludes a holding portion configured to hold said shaft portionrotatably and to hold said shaft portion movably in a direction crossinga sheet conveying direction at a reading position of said reading unit,and wherein in a state in which said reading unit is rotated to aposition where said transparent member is exposed to the outside of saidimage reading apparatus, said reading unit is movable in the directioncrossing the sheet conveying direction.
 13. An image forming apparatusaccording to claim 1, further comprising an electric wire connected tosaid reading portion and configured to transmit the image informationread by said reading portion, wherein said reading unit includes anopening through which said electric wire is lead to the outside of saidreading unit, and wherein as viewed in a sheet widthwise direction, adistance from the third rotational axis to said opening is shorter thana distance from the second rotational axis to said opening.
 14. An imagereading apparatus according to claim 13, further comprising a frame,wherein said reading unit includes a shaft portion provided on the thirdrotational axis, wherein said frame comprises a holding portionconfigured to hold said shaft portion rotatably, and wherein as viewedin the sheet widthwise direction, said electric wire wired through saidopening and said shaft portion overlap with each other.
 15. An imagereading apparatus according to claim 14, wherein said reading unit has arectangular shape as viewed in the sheet widthwise direction, andwherein as viewed in the sheet widthwise direction, a corner portion ofsaid reading unit closest to said shaft portion and a corner portion ofsaid reading unit closest to said opening are the same.
 16. An imagereading apparatus according to claim 1, wherein said cover unit includesan upper side guiding surface for guiding an upper side surface of thesheet, wherein said conveying guide includes a lower side guidingsurface which forms the sheet conveying passage in cooperation with saidupper side guiding surface and which is for guiding a lower side surfaceof the sheet, and wherein the third rotational axis is positioned belowsaid upper side guiding surface and said lower side guiding surface. 17.An image reading apparatus according to claim 16, further comprising: astacking portion on which the sheet is stacked; and a discharge portionprovided below said stacking portion and configured to discharge thesheet from which the image information is read, wherein as viewed in asheet widthwise direction, the sheet conveying passage is curved so thatthe sheet is fed from said stacking portion toward one side of ahorizontal direction and is discharged toward the other side of thehorizontal direction, wherein said conveying guides the lower sidesurface of the sheet fed from said stacking portion toward said one sideof the horizontal direction, and wherein said reading unit is disposedbelow said conveying guide and inside the curved sheet conveyingpassage.
 18. An image reading apparatus according to claim 1, whereinthe second rotational axis is provided at an upstream side end portionof said conveying guide with respect to a sheet conveying directionalong which the sheet is guided by said conveying guide, wherein thethird rotational axis is provided at a downstream side end portion ofsaid reading unit with respect to the sheet conveying direction alongwhich the sheet is guided by said conveying guide, and wherein when saidconveying guide and said reading unit are rotated so that saidtransparent member is exposed to the outside of said image readingapparatus, a rotational direction of said conveying guide and arotational direction of said reading unit are opposite to each other.19. An image reading apparatus according to claim 1, wherein the secondrotational axis is provided at an upstream side end portion of saidconveying guide with respect to a sheet conveying direction along whichthe sheet is guided by said conveying guide, wherein the thirdrotational axis is provided at an upstream side end portion of saidreading unit with respect to the sheet conveying direction along whichthe sheet is guided by said conveying guide, and wherein when saidconveying guide and said reading unit are rotated so that saidtransparent member is exposed to the outside of said image readingapparatus, a rotational direction of said conveying guide and arotational direction of said reading unit are the same direction.
 20. Animage reading apparatus according to claim 1, wherein the secondrotational axis is provided at a downstream side end portion of saidconveying guide with respect to a sheet conveying direction along whichthe sheet is guided by said conveying guide, wherein the thirdrotational axis is provided at a downstream side end portion of saidreading unit with respect to the sheet conveying direction along whichthe sheet is guided by said conveying guide, and wherein when saidconveying guide and said reading unit are rotated so that saidtransparent member is exposed to the outside of said image readingapparatus, a rotational direction of said conveying guide and arotational direction of said reading unit are the same direction.
 21. Animage reading apparatus according to claim 1, wherein the secondrotational axis is provided at a downstream side end portion of saidconveying guide with respect to a sheet conveying direction along whichthe sheet is guided by said conveying guide, wherein the thirdrotational axis is provided at an upstream side end portion of saidreading unit with respect to the sheet conveying direction along whichthe sheet is guided by said conveying guide, and wherein when saidconveying guide and said reading unit are rotated so that saidtransparent member is exposed to the outside of said image readingapparatus, a rotational direction of said conveying guide and arotational direction of said reading unit are the same direction.
 22. Animage forming apparatus comprising: an image reading apparatusconfigured to read image information from a sheet; and an image formingmember configured to form an image on a recording material on the basisof the image information read by said image reading apparatus, whereinsaid image reading apparatus includes: a cover unit provided rotatablyabout a first rotational axis and including an upper surface of saidimage reading apparatus; a sheet conveying member configured to conveythe sheet along a sheet conveying passage; a conveying guide providedrotatably about a second rotational axis different from the firstrotational axis and configured to guide the sheet fed by said sheetconveying member; and a reading unit which includes a transparent memberand a reading portion configured to read, through said transparentmember, an image on the sheet fed by said sheet conveying member andwhich is provided rotatably about a third rotational axis different fromthe first rotational axis and the second rotational axis, wherein saidcover unit is rotatable between a closed position where said cover unitforms the sheet conveying passage in cooperation with said conveyingguide and an open position where the sheet conveying passage is open,and wherein in a state in which said cover unit is positioned in theopen position, said transparent member is exposed to an outside of saidimage reading apparatus by rotation of said conveying guide and saidreading unit.
 23. An image reading apparatus for reading imageinformation from a sheet, comprising: a sheet conveying memberconfigured to convey the sheet along a sheet conveying passage; areading unit which includes a transparent member and a reading portionconfigured to read, through said transparent member, an image on thesheet fed by said sheet conveying member and which is provided rotatablyabout a rotational axis between a first position where said transparentmember opposes the sheet conveying passage and a second position wheresaid transparent member is exposed, wherein in a state in which saidreading unit is positioned in the first position, said transparentmember faces downward in a vertical direction, and wherein in a state inwhich said reading unit is positioned in the second position, saidtransparent member faces upward in the vertical direction.